Subsequent Events - Additional Information (Detail) (USD $)	3 Months Ended		1 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Apr. 30, 2015
Forecast [Member]
Subsequent Event [Line Items]
Deferred financing costs	$ 2,000,000
$400 Million 5% Senior Notes [Member]
Subsequent Event [Line Items]
Interest rate of Senior Notes		5.00%
Maturity date for notes		Apr. 15, 2023
Maturity year of note		2023
Senior note, repayment terms		Payable semi-annually in cash in arrears on April 15 and October 15 of each year, beginning October 15, 2015
$1 Billion Credit Facility [Member]
Subsequent Event [Line Items]
Total credit facility		1,000,000,000
Subsequent Event [Member] | $400 Million 5% Senior Notes [Member]
Subsequent Event [Line Items]
Interest rate of Senior Notes			5.00%
Senior notes, principal amount			400,000,000
Net proceeds from issuance of senior notes			392,000,000
Subsequent Event [Member] | $1 Billion Credit Facility [Member]
Subsequent Event [Line Items]
Total credit facility			1,000,000,000
Subsequent Event [Member] | $1 Billion Credit Facility [Member] | Senior Secured Term Loan Facility [Member]
Subsequent Event [Line Items]
Total credit facility			$ 300,000,000